BerdAir pump controlling

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teeminus
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BerdAir pump controlling

Post by teeminus »

Hi!

I just got my airpump and I was suprised how much air flow this thing produces. I had to run the pump on 12VDC instead of 24VDC because otherwise Marlin would halt with a thermal runaway error. Maybe this is caused by non optimal drill holes in the metal pipes but I have not further investigated that.

The point I was thinking about is how to control the pump from the mainboard. When using colling fans they are driven by a PWM signal. I knew that the pump won't like the PWM signal but out of curiosity I connected the pump to an externmal mosfet that was driven by the PWM signal of the fan - not a very good idea unless your duty cycle is close to 100% :-D
So for testing purposes (and to print the last parts as my current fan duct sucks) I hooked the pump to a bench supply and turned it on manually. That works for this temp. setup but will not work for the final assembly.

Thats why I am reaching out to you guys to ask:
  1. How do you control these pumps?
  2. Do you even control your pump or are the always on? Or more like a binary switch, either completely on or completely off.
  3. What's you max. % you run your pumps on?
Kind regards
Christian
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MirageC
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Re: BerdAir pump controlling

Post by MirageC »

In order to avoid the heater fault code with a stronger fan you need to perform you PID tune with printing condition replicated as much as possible. Fan/bed (I even tried one day with filament extrusion... massive pile up :) ). This will redefine the heater profile and you printer will know what is the new Normal condition.

As for Pump control, The PWM frequency is what needs to be modifiedfor them to be adjustable. Normal Fan have a PWM at 255Hz, I run my Kamoer pump at 20KHz to obtain a better control.
I usually run 100% fan for PLA with no issue. Pressure can be enough to push filament downwards during bridge printing so be careful.

teeminus
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Re: BerdAir pump controlling

Post by teeminus »

Do you use any additional electronics like a diode or a current limitter?
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Re: BerdAir pump controlling

Post by MirageC »

No, My pump is brushless and required 0.9 Amp which is within what the duet can manage.

teeminus
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Re: BerdAir pump controlling

Post by teeminus »

Oh, wow. I am using a SKR Pro board which only has a tiny SOT23 FET to drive the fan.

Anyways, thanks for the feedback. I will see if I can get the pump working properly once the rebuild is done.
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